Alkaline in situ transesterification of Chlorella vulgaris

► Process variables for alkaline in situ transesterification of microalgae were evaluated. ► At low catalyst ratios, using NaOH produced higher FAME yields than H2SO4. ► Using NaOH required less time than H2SO4 to obtain high FAME yields. ► Maximum FAME yield of 77.6 ± 2.3 wt% was obtained using NaOH as catalyst. ► Maximum FAME yield of 96.8 ± 6.3 wt% was obtained using H2SO4 as catalyst.